Mans' involvement with the oceans is steadily growing and changing. Once used strictly as a medium of transport and source of nourishment, the oceans are now considered as a last, earthbound frontier for continued sustentation. As industrial development of this unsettled environment advances, a need arises for energy systems which provide electrical service power for remote area applications such as signalling and monitoring equipment, resource recovery operations, and large scale desalination processes or hydrogen production. Autonomous systems are needed to supplant present methods of onshore/offshore electrical provision for these methods are dependent on regeneration from land based sources. For example, the practice of using battery powered audio/visual signalling or data acquisition equipment can require a user to execute repeated service and component replacement operations during a performance period. The frequency of these costly maintenance procedures is extensively reduced when utilizing the indigenous power generation means provided by an apparatus for converting the hydrokinetic energy of water wave fluctuations to electrical energy. Wave motion has long been recognized as a substantive resource and invention relating to this subject is copious. However, commercial development and utilization has been greatly restrained due to the inherent functional limitations of various prior devices. One common disadvantage is the absence of design consideration for modulation by which methodology a basic module is interconnected to other similar modules thus forming a system array. With some exception, the field is replete with devices comprising unitary non-systems that would not advantageously utilize the diffuse, planar expanses of fluctuative energy which embody the wave environment. Such devices are exemplified in the Schera, Jr. U.S. Pat. No. 3,898,471 and the Tornabene U.S. Pat. Nos. 3,930,168 and 3,964,264.
In one embodiment of the Schera, Jr. U.S. Pat. No. 3,898,471, there is disclosed a float operated electrical generator consisting of a vertical slotted member 28 enclosing a movable rack 37 with attached float 29, said rack 37 being retained in engagement to a pinion gear 36 mounted on the driveshaft of a stationary electrical generator 34. Although shown supported by a concrete base 1, the apparatus may be affixed to the side of a dock, boat, or other marine structure. In operation, wave induced reciprocal float/rack movement causes bidirectional rotation of the gear/generator and electricity is produced for signalling functions. Although conversion is direct, the absence of kinetic energy storage reduces electrical generation frequency during float/rack stroke reversal and provides no accumulation of stored energy as resultant from the input of successive strokes. Furthermore, deployment of the apparatus is limited to the availability of the aforementioned support structures.
One embodiment of the Tornabene U.S. Pat. No. 3,930,168 describes a wave actuated float 16 of sufficient water displacement capacity and dense mass to enhance inertia and momentum during upward and downward movements, said float 16 being attached, in non-binding mode, to a vertically reciprocable shaft 26 retained by bearings 27,28 in a structure embedded in the sea floor and in a structure extending out of the water 34,40, said outwardly extending structure being joined to said submerged structure by supports 35. The shaft 26 carries a rack in driving engagement to a gear 37 affixed on a common axle 38 between two electrical generators 39 disposed on said outwardly extending structure platform 34. This embodiment is essentially similar in operation to the Schera, Jr. U.S. Pat. No. 3,898,471 with exception of the non-binding float/shaft connection and the optional provision of dense mass associated with the float for increasing downward forces of the shaft. Rather than improving electrical generation efficiency, however, such an associated float mass impedes upward float/shaft movement after submergence. Conversely, downward forces of the dense mass are partially negated by float lift. Resultantly, the reciprocation frequency of the float is lower than ambient wave frequency thus causing partial cessation and slower output speeds during normal operation. Additionally, as evidenced in a Schera, Jr. U.S. Pat. No. 3,898,471 embodiment, the necessity of extensive ground attachment means for supporting the energy converting mechanisms limits deployment of the apparatus to relatively shallow waters.
The Tornabene U.S. Pat. No. 3,964,264 identifies a wave action undersea drilling rig which does not relate to the mechanisms or functions of the present invention.
The second preferred embodiment of the Solell U.S. Pat. No. 4,145,885 defines an elongated housing 102 mounted on columns 104 above a body of water and extending perpendicularly to the direction of wave travel, said housing 102 therein supporting a plurality of vertically reciprocable racks 120 by bearings 122,124, said racks 120 being equipped, at the lower end, with respective floats 112. Two elongated driveshafts S1,S2 are commonly engaged to the rack 120 plurality of respective overrunning clutch gears 148,150 so that upward rack movement drives one shaft and downward rack movement drives the other shaft in the opposite direction of rotation. A common output shaft S0 is suitably connected with the driveshafts S1,S2 to be thereby driven in one direction of rotation. Accordingly, this shaft may be connected to a generator, pump, or other device. The mechanical unification of disparately operative point absorbers attributes to centralization of energy conversion means which must be responsive to extensively variable force inputs ranging from slight movement of a single point absorber to substantial movement of all point absorbers. The absence of suitable transmission or momentum storage means for accommodation of variable force inputs reduces the efficiency of the device when optimal wave conditions are not present. As described in prior art, utilization of the device is functionally dependent on rigid, ground connected structures for maintaining the housing with components above water level. Furthermore, omnidirectional deployment of a wave motor plurality along the horizontal plane covers and dampens the source of energy from which they operate.
The Paolucci International Pat. No. WO 81/00284 shows an elongated housing 5,30 positioned above a body of water by anchored buoys 20,36 with supports 19. The housing 5,30 contains an elongated, rotary driveshaft 2 provided with several ratchet sprocket wheels 8a,8b in respective engagement to a plurality of vertically reciprocable drive assemblies 14 with respective floats 18 disposed at the lower end. A drive assembly 14 is arranged to impart unidirectional driveshaft 2 rotation irrespective of reciprocation direction. For this purpose, the drive assemblies 14 are sufficiently weighted for equalizing power take-off from the buoyancy force in the upward direction and the gravity force in the downward direction. Accordingly, the ends of the driveshaft 2 are connected to counter-rotating flywheels 31,33 which are, in turn, connected to respective electrical generators 6 mounted in the housing 30. Although forming no part of claimed matter, a transmission 34 is shown between a flywheel 31,33 and generator 6 for changing the speed of rotation as desired. The use of neutral stabilization means such as anchored buoys 20,36 forms an improvement in selfsustention capability over the Solell U.S. Pat. No. 4,145,885 and other art. However, separation of the neutral buoyancy maintenance function 20 from the above water housing provision function 5,30 renders unnecessary structural redundancy and dampens wind generated surface wave activity. Deployment of additional drive assemblies 14 and anchored buoys 20,36 along the common output driveshaft 2 is limited to uniaxial connections which necessitate replacement of the flywheels 31,33, transmission 34, and generators 6 for accommodation of the reformed kinetic energy input range. The provision of flywheels 31,33 diminishes start-up torque loading and moderates continuous output rotational velocity from the kinetic energy storage and accumulation of successive drive assembly 14 strokes though, as described for the Solell U.S. Pat. No. 4,145,885, efficient conversion of the extensive input force range remains problematic. Additionally, the use of float associated dense mass for increasing downward momentum causes wave/float frequency matching obstacles similar to those elucidated for the Tornabene U.S. Pat. No. 3,930,168.
The Ames U.S. Pat. No. 4,232,230 discloses a modular assembly of reciprocating electrical generators arranged as edge elements of a tetrahedron, said respective generator outer portions comprising tubular members 1 joined in non-intersecting relationship by a common block 2 near the apex and by respective lower brackets 5 affixed to a common damper plate 4 with movable ballast weights 6. A closed air chamber 3 is secured to the tubes 1 below the block 2 for maintaining neutrally buoyant suspension of the assembly with respect to the mean sea surface. Each generator inner portion consists of bearings 11 supporting a coaxial rod 7 provided, at its upper end, with a respective float 8 of spherical shape. A sealable bellows sleeve 12 is suitably mounted on a rod 7 and tube 1 for providing flexible closure. Each rod 7 carries a plurality of longitudinally spaced permanent magnets 10. A plurality of coaxially extending coils 15 are located about a rod 7 and magnets 10 within a tube 1 so that an associated magnet 10 moves from positions enclosed by a coil 15 to positions outside of coil 15 during normal reciprocation. The coils 15 of a generator are series-connected to a rectifier 21 and capacitor 19 which are, in turn, seriesconnected to other rectifier coils 15 of a module and to conductors 15A contained in upper tubes 17 connecting to other modules of an array or to external utilization means. Accordingly, respective lower module portions are suitably interconnected by brackets 5 to form a module array of any desired quantity. In operation, wave procession raises and lowers the floats 8 and respective rod 7 and magnet 10 assemblies through the coils 15 which are maintained relatively stationary in the air chamber 3 by the associated damper plate 4. This relative movement induces pulses of electromotive force in the coils 15 which are additively combined with the outputs of other independent generators by the described series-connection. The functional unification of energy conversion means housing and neutral buoyancy maintenance by the air chamber eliminates the type of structural redundancy evidenced in the Paolucci Pat. No. WO 81/00284 while providing a self-stabilized and modularly expandable system of independently operative generators which requires only light bottom anchorage to counteract off-station drifting. Additionally, deployment of modules below the water surface negates the interference and dampening of wind generated surface wave activity on the working floats 8, as evidenced in the Solell U.S. Pat. No. 4,145,885 and the Paolucci International Pat. No. WO 81/00284. The fully independent operation of the floats 8 and associated generators also serves to limit variability of engaging input forces resulting in a more efficient conversion range while providing centralized accumulation of electrical energy rather than kinetic energy. Furthermore, the use of electrical energy transmission and storage means becomes increasingly more efficient than kinetic energy transmission and storage means with expansion of a module array over relatively large areas. In addition to the structural advantages of a tetrahedral module, the implementation of respective inclined reciprocation axes geometrically extends the length of stroke by nearly 20% relative to the vertical axes shown in the prior art. If suitably positioned relative to wave direction, the inclined axes also expand the floats' capture width by 33% due to their simultaneous absorption of both the vertical force component of buoyancy and the horizontal time component of float 8/wave crest engagement with respect to wave procession. This feature greatly improves the wave-following capability of a float 8 while sustaining applied loads such as from generator elements or other energy conversion means.
Reduction to practice included wave tank testing of a working model according to this invention. This test was performed for observing the mechanical and electrical operations under controlled conditions. Although considered successful, the test indicated several deficiencies which included the float 8 shape with regard to wave engagement. Evidently, the spherical shape of respective floats 8 provided little tangential surface resistance to water particle motion while promoting a variable submergence rate which resulted in the establishment of a non-resonant float 8 actuation delay. Often, this delay nullified reciprocation of the rods 7 and associated magnets 10 due to their antiphasal movement with the ambient wave field. This condition indicated that improved wavefollowing capability could be derived from float 8 shapes having low centers of buoyancy and maximal planar contact with the hydroface. Actuation time delay was augmented by the direct use of float 8 displacement for raising and lowering associated linear magnet 10 arrays through the coils 15. Although energy conversion was very direct, the weight of float 8 associated magnet 10 arrays caused wave/reciprocation frequency matching problems similar to those percieved and described for the Tornabene U.S. Pat. No. 3,930,168 and the Paolucci International Pat. No. WO 81/00284. This linear generator was also inefficient due to the necessary provision of a relatively large quantity of longitudinally spaced magnets 10 in relation to the number of coils 15 so that, at any instant during normal reciprocation, at least some of the magnets 10 would move from positions into and out of the coils 15. Furthermore, the arrangement did not utilize kinetic energy storage and accumulation of successive strokes for increasing continuous electrical generation. Resultantly, power generation was diminished during stroke reversal and start-up. These linear generator problems indicated that enhanced electrical production could be obtained from means for converting the respective rod 7 reciprocable motion to rotary motion of kinetic energy storage and transmission means which propel standard generators. Therefore, an object of the present invention is to overcome and/or obviate the difficulties and disadvantages of prior art by provision of an ocean wave energy converter which utilizes various improvements and advantages, to be further described.